More than a month before 17 people were killed at a Florida high school, the FBI got a tip warning that the suspect wanted to kill people and was planning to carry out a school shooting.

The tipster also said Nikolas Cruz owned guns, was acting erratically and had made disturbing social media posts.

The information provided by the caller should”ve been assessed as a potential threat to life and passed to a field office, the FBI said. But it never reached agents in Florida and no investigation was launched.

It was one of hundreds of thousands of tips received annually by the FBI”s public tip line  1-800-CALL-FBI. Here”s a look at how the agency analyzes tips:

WHAT HAPPENS WHEN YOU CALL THE FBI TIP LINE?

Representatives at the public access line  the bureau”s tip center in West Virginia  are responsible for taking information from the public.

If a tip appears credible and warrants further investigation, it is supposed to be forwarded to an FBI field office.

Other tips sometimes involve non-criminal incidents and aren”t passed along, while threats against politicians, including the president, could be referred to the Secret Service.

Before the call center opened in 2012, field offices handled their own tips, which could inundate agents.

Officials have encouraged the public to use the line after nearly every major U.S. terror attack or mass shooting in the past few years.

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HOW MANY CALLS ARE RECEIVED?

On average, more than 2,100 calls were received each day in 2017, and the more than 150 employees who work for the tip line answered a total of 766,888 calls for the year.

Since the tip line opened, it has received more than 2 million calls that resulted in thousands of actionable tips and leads for special agents and intelligence analysts, the FBI says.

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WHAT SHOULD”VE HAPPENED WITH THE TIP ABOUT NIKOLAS CRUZ?

The information should have been “assessed as a potential threat to life,” the FBI said, and forwarded to the agents in the Miami field office to investigate.

The FBI and Department of Justice are investigating why the tip about Cruz was not sent to field agents.

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WHAT KIND OF TRAINING DO CALL-TAKERS RECEIVE?

Attendants are trained to gather information that might aid investigations. They are taught listening and communications skills, undergo classroom training and receive on-the-job training with other representatives to learn how to write reports.